Presentation NAEM 2014

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Published on February 25, 2014

Author: basdingemans

Source: slideshare.net

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Presentation about the tea bag index given at the Netherlands Annual Ecology Meeting February 2014

The Tea Bag Index Bas Dingemans Joost Keuskamp Judith Sarneel Taru Lehtinen Mariet Hefting Abi Ashton [Faculty of Science Biology]

Soil Map /Decomposition At the Wageningen postgraduate soil ecology course in 2010, we were asked to come up with an interesting parameter missing from the global soil map. We thought: What’s more interesting for soil functioning and climate change than decomposition? But how to obtain a worldwide measured parameter for decomposition? Faculty of Science Biology

Experiments /Litterbags One method to analyse decomposition rate in the field is measuring litter mass loss using litter bags. Making litter bags (weighing, sealing or sowing) is time consuming. Moreover, to get an overview of decomposition rate and carbon sequestration, one has to do various measurements in time. Photo: LogLife Experiment Poster 103 [Faculty of Science Biology]

Tea Bags /Litterbags To collect data on decomposition at a large scale and density, a much easier, cheaper and better standardised method is needed. Some brands of tea use nylon bags, very similar to litter bags. The tea inside the bags resembles dried plant material used in litter bag studies. These tea bags can be used as prefabricated litter bags. [Faculty of Science Biology]

Tea Bags /Decomposable Green tea decomposed faster than rooibos tea and reached the fase where decomposition stagnates faster than rooibos tea. Our goal was to get as much information as possible out of one harvest in time. 1.0 Relative Mass Remaining (g g-1) After extensive experimenting burying different tea types, we chose two tea types that differed in decomposability: Green tea and Rooibos tea. Rooibos tea 0.8 0.6 0.4 Green tea 0.2 0.0 0 10 20 30 Time (days) 40 50 60 [Faculty of Science Biology]

Tea bags /C fractions Green Tea We used chemical composition analyses and linked that to decomposability. Compared to rooibos tea, green tea contains a lot of water soluble carbon, while rooibos tea contains more acid insoluble carbon. Therefore Rooibos tea is more recalcitrant and decomposes slower than the green tea. 0.15 Rooibos Tea 0.00 0.03 0.00 0.03 0.22 0.37 0.30 0.52 0.37 Non-polar extractables Water solubles Acid solubles Acid insolubles Mineral fraction [Faculty of Science Biology]

Tea Bag Index /Calculations From the weight loss and the initial chemical composition of the tea we calculate two parameters, comprising the TBI: Decomposition rate k A measure for turnover time of labile carbon Stabilisation factor S A measure for stabilisation potential of organic carbon [Faculty of Science Biology]

Tea Bag Index /Calculations We modelled decomposition after Brock et al. (1985) as an exponential decay curve operating at two pools: a labile and a recalcitrant carbon pool. W(t)=a e-kt + (1-a) where W(t) is the mass fraction remaining at time t, a is labile pool fraction and k is initial decomposition rate of the labile pool. We assume that the mass loss of the recalcitrant pool is negligible. Relative Mass Remaining (g g-1) 1.0 0.8 0.6 Rooibos tea 0.4 Green tea 0.2 0.0 0 20 40 60 80 Time (days) 100 120 140 [Faculty of Science Biology]

Tea Bag Index /Calculations S is calculated from the green tea results: S = 1 - ag / Hg where ag is the decomposable fraction of Green tea based on the mass loss in the field and Hg is the hydrolysable fraction of Green tea. S can be interpreted as the inhibiting effect of environmental conditions on decomposition of labile litter fraction Relative Mass Remaining (g g-1) 1.0 0.8 ag 0.6 0.4 Green tea 0.2 0.0 20 0 0.15 40 60 80 Time (days) 120 140 0.00 0.03 Hg{ 0.30 100 0.52 Non-polar extractables Water solubles Acid solubles Acid insolubles Mineral fraction [Faculty of Science Biology]

Tea Bag Index /Calculations Because the decomposable fraction of Red tea (ar) cannot be determined in the field in a short-term incubation period, we estimated ar under the assumption that S is equal for Green and Rooibos tea: Relative Mass Remaining (g g-1) 1.0 ar 0.8 0.6 Rooibos tea 0.4 0.2 0.0 ar = Hr (1 - S) 0 where Hr is the hydrolysable fraction of Red tea. 20 40 60 80 Time (days) 100 120 140 0.00 0.03 0.22 0.37 H r{ Non-polar extractables Water solubles Acid solubles Acid insolubles Mineral fraction [Faculty of Science Biology] 0.37

k is now calculated by linearising and solving the exponential decay function for the labile litter pool: Wr(t) = ar e + (1-ar) -kt ln(ar)-ln(Wr(t))-(1-ar) k= t Decomposition rate (k) Tea Bag Index /Calculations 13* 0.03 14 0.02 0.01 5 16 9 10 15 17 6 11 4 2 12 3 1 7 US-FL mangrove-dwarf US-FL mangrove-fringe IE peat-disturbed IE peat-undisturbed IS grassland-warmed IS grassland-ambient CN desert-sandy CN desert-loamy NL forest NL wet forest NL pasture NL peat PA forest AU mixed forest AU birch forest Lab 25°C Lab 15°C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 8 0.00 0.00 .1 0.20 .3 0.40 .5 0.60 .7 Stabilisation factor (S) Keuskamp, Dingemans et al. 2013, Methods in Ecology and Evolution [Faculty of Science Biology]

Iceland Research /Iceland An example of successful implementation of the TBI method is research in Iceland. In a geothermally heated valley with plots on cold and heated soil with comparable soil conditions. Reykjavik Hveragerdi Land age < 0.8 M j 0.8 - 3.3 M j 3.3 - 15 M j [Faculty of Science Biology]

Water flow Research /Iceland Plots were placed in 2005 on warmed and ambient soil and fertilised annually with N. Between May and August 2011 we buried tea bags to understand the effects of warming and fertilisation and their interactive effect on decomposition. Control Fertilised 25 Soil temperature (°C) Plots consisted of two adjacent subplots, a fertilised and an upstream control. Plot Ambient Warmed 20 15 10 5 0 Control Fertilised treatment [Faculty of Science Biology]

Research /Iceland We buried a pair of green and rooibos tea bags in 80 plots and I was very happy to find most of them back after 3 months. [Faculty of Science Biology]

Research /Iceland Neither warming nor fertilisation had effect on the decomposition rate, however the stabilised fraction of tea in warmed plots was lower and, in the ambient plots, fertilisation caused a lower stabilised fraction of tea. Decomposition rate (k) 0.03 UA 0.02 UW FA FW 0.01 0.00 0.0 0.1 0.2 Stabilised fraction (S) 0.3 Dingemans et al. 2014, in prep. [Faculty of Science Biology]

Tea Bag Index /Application Apart from using tea bags as an estimator for environmental effects on organic carbon sequestration in scientific experiments, TBI is very suitable for: Large scale/high density measurements (crowdsourcing) Global/european soil map of decomposition Education/ public awareness campaigns [Faculty of Science Biology]

Tea Bag Index /Crowdsourcing The simplicity and low resource requirements make the TBI suitable for crowdsourcing. We ask teadrinker worldwide to cooperate with our experiment. They just have to bury two tea bags and weigh them after 3 months. @ decolab.org/tbi production weighing harvest tea bags distribution bury tea bags 3 months in soil [Faculty of Science Biology]

Tea Bag Index /Soil Map The results from these individual experiments have the potential to result in a parameter for decomposition in the global soil map. [Faculty of Science Biology]

Tea Bag Index /Education The tea bag experiments are suitable for various types of teaching activities. It visualises decomposition per se but also more complex problems can be addressed. [Faculty of Science Biology]

Tea Bag Index /Future success Method is accepted within the scientific community, but now... We still aim to make the method more userfriendly. Continuation and constant quality of Lipton tea and tea bags. Global distribution Implementing the parameter in a global soil map. Faculty of Science Biology

facebook.com/teabagindex @TeaBagIndex www.decolab.org/tbi on behalf of the TBI team, thanks! [Faculty of Science Biology]

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